Complementary and alternative medical (CAM) treatments are increasingly being used by patients with chronic pain and rheumatic diseases to help them cope with difficult symptoms and stress associated with their condition. While patients find these treatments helpful, there is limited scientific evidence for the efficacy of these interventions. It is undetermined whether these interventions have significant effects on disease activity or affect health outcomes in afflicted patients. The purpose of the proposed project is to compare a novel alternative intervention, Tai Chi Chih (TCC; a manualized, standard form of Tai Chi) with a commonly used intervention, relaxation therapy (RC), on measures of clinical outcomes (disease activity, health functioning) in adults with rheumatoid arthritis (RA). Our preliminary data have shown that administration of TCC in a randomized controlled trial leads to improvements in physical functioning and immunity in healthy older adults. This research compares the clinical efficacy of TCC against an active treatment control, RC, in a medically ill population, to determine whether the effects of TCC are relevant to disease outcomes and whether they exceed the effects of a "relaxation response" or that due to the attention and support common to group interventions. In addition, we explore the biobehavioral mechanisms (pro-inflammatory cytokines, affective response) through which TCC may contribute to improvements in the health of RA patients. Sixty persons with active RA will be stratified according to medication use and randomly assigned, following pre-treatment evaluations, to one of two treatment groups (TCC vs. RC). Participants are evaluated again at mid-treatment and immediately following a 12-week course of TCC or RC. The results of this study will advance our understanding of the effects of a novel CAM intervention, TCC, on relevant clinical outcomes in persons with RA and will provide preliminary data for future research of the biobehavioral mechanisms underlying the effectiveness of TCC.